Train printers

ABSTRACT

A train printer cartridge and print slug arrangement having a closed loop guide track for non inter connected print slugs freely slidable in the guide track and each having a single drive tooth on each side of the slug, the teeth meshing with notched drive wheels. The track arrangement permits the slugs to move from abutting contact whilst meshing with the wheels and also enables transformation of angular motion around the wheels to the straight line motion for advancing to the printing section to be completed before the slug leaves the drive wheels.

United States Patent 11 1 Dere 11] 3,814,012 June 4, 1974 TRAIN PRINTERS[75] Inventor: Roman Derc, Letchworth, England [73] Assignee:International Computers Limited,

London, England [22] Filed: July 20, 1972 [21] Appl. No.: 273,594

[30] Foreign Application Priority Data 12/1963 Simpson 101/111 3,379,1267/1966 Stalleretall 101/382 3633501 9/1969 Edwards 101/111 PrimaryExaminer-J. Reed Fisher Assistant Examiner-Paul J. Hirsch Attorney,Agent, or Firm-Hane, Baxley & Spiecens 1 7 ABSTRACT A train printercartridge and print slug arrangement hay nga closed loop guide traclifor non 1115656611 ne cted print slugs freely slidable in the guidetrack and .each having a single drive tooth on each side of the slug,the teeth meshing with notched drive wheels. The track arrangementpermits the slugs to move from abutting contact whilst meshing with thewheels and also enables transformation of angular motion around thewheels to the straight line motion for advancing to the printing sectionto be completed before the slug leaves the drive wheels.

'5 Claims, 6 Drawing Figures PATENTEDJuu 4 I974 SHEET 2 [IF 2 I TRAIN.PRINTERS BACKGROUND OF THE INVENTION The invention relates to trainprinters.

In a train printer print slugs, each bearing a few characters push eachother in guides round a closed-loop, generally oval, track having atleast one straight portion at which printing takes place. The slugs arenot connected to each other and have integral teeth by which they aredriven at part of the track, for example by a toothed drive wheel ateither, or both, ends of an oval track. Some clearance is necessary inthe guides and,

According to the invention there is provided a train printer print slughaving a body portion with teeth for engaging with a toothed drivingwheel of a train printer, characterised in that the slug has a singlecentrally disposed tooth at each side of the body portion.

Preferably in accordance with an aspect of the invention a train printercartridge comprises guide means defining a closed-loop track for printslugsaccor ding to the invention, the track having a straight portionextending from a curved portion about a toothed drive wheel for meshingwith teeth of the slugs to drive them into the straight portion, onepart of the guide means permitting slugs being driven to move radiallyoutwardly of the drive wheel without losing driving engagement, andanother part co-operating with surfaces of a slug to bring that sluginto alignment with the straight track portion before the centre. ofthat slug reaches the perpendicular from the driving wheel axis tothestraight portion.

The slugs will thus have their rotational movement round the drivingwheel transformed to rectilinear movement prior to leaving the drivingwheel. The avoidance of coincidence of these two actions reduces BRIEFDESCRIPTION OF THE DRAWING One embodiment of the invention will now bedescribed, by way of example, with reference to the accompanyingdrawings,'in which:

FIG. I shows, diagrammatically, parts of a train printer cartridge;

FIG. 2 is a side view of a print slug;

FIG. 3 is an end view of a print slug;

FIG. 4 is a section through the teeth of a slug drive wheel; 1

FIG. 5 is an enlarged view of a detail of the cartridge of FIG. 1; I

FIG. 6 is a part section on the line 22 of FIG. 1.

DESCRIPTION OF PREFERRED EMBODIMENT In the illustrated train printercartridge, a series of print slugs 11 are passed along a generally ovaltrack between inner and outer guide surfaces 12 and 13, respectively.The slugs 11 are separate an d are driven only at the ends of the trackby toothed drive wheels 114; In between these drive wheels, the slugsabut at their ends to push each other along 'a straight part of thetrack. Alongside one such straight part is a printing hammer block 15.In operation, paper and an inked web are present between the hammerblock 15 and the print slugs II and, as the latter pass by,ballistic hammers within the block l5 are fired at appropriate times to press thepaper and ink web against the characters borne by the slugs 11. Theprint bearing portions of the slugs protrude through spaced parts of theouter guide surfaces 13.

chatter of the slugs and enables printing to take place nearer thedriving wheel.

Since'the slug has a single tooth disposed substantially centrally oneach side thereof, driving forces from the driving wheel teeth will begenerally symmetrical relative to the centre of gravity of a slug. Thisavoids the kinds of movement on the slug that result for slugs operatingwith outer guides of the guide means. These shoulders may flank anupstanding character bearing surface and are sloped at each end. Theseslopes, to gether with slopes on the tooth edges and the ends of theslug co-operate in achieving the above mentioned prior alignment withthe straight track portion. v

It is convenient for the inner guide surface 12 to comprise the edgesurface of an ovalplate 49, and each of the outer guide surfaces 13 tocomprise the inner side surface of an edge flange on a generally ovalcover 13A for each face of the oval plate.

The outer guide surfaces 13 are curved about the drive wheel 14 andspaced therefrom by a, distance greater than the distance between thesurfaces 12 and 13 along the straight portion of the track to allow theslugs to'move radially outwardly of the drive wheel without losingdriving engagement, and be brought into alignment with their directionoftravel along the straight parts ofthe track prior to each slug leavingthe teeth of the drive wheels, in factpriorto its centre reaching topdead centre. This results from the transition from curved to straight inthe outer guide surfaces 113 and improves the way in which the slugs 11travel past thehammer block 15, and alsov enables the latter to benearer to top dead centre of the left hand drive,

FIG. I, would in practice, correspond with front" and back respectively.

Instead of being in abutting, or near-abutting relation, the slugs 11 inthe curved part l3, are slightly spaced as indicated by the gap 19 inFIG. 1. The transi- 3 tion of the guide surface 13 from curved tostraight at position 21 prior to top dead centre 22 marks the beginningof tipping of a slug forwards to achieve alignment with the track pastthe hammer block at a position 23 prior to the centre of theslug-coinciding with top dead centre 22. Transformation of angularmotion into rectilinear motion is thus achieved prior to a slug leavingthe teeth of the drive wheel, which occurs at top dead centre 22. Thisaction reduces irregularities of subsequent slug motion.

Each slug 11 has a single centrally disposed tooth 26 on each side.These teeth 26 taper so that their upper surfaces 27 extend furtheralong the slug. The slide surfaces 27 are extensions of stepped centralparts 28 of the slug along body portion 30A to either side of anupstanding character 29 bearing portion 30. At each end, the centralstepped parts 28 have extensions 31 inclined downwardly. Along straightportions of the slug track, the outer guide 13 will contact the centralstepped parts 28. The-stepped parts 31 are inclined more than would berequired for them to make chords on the curved part of the upper guide.This allows a slug to be tipped forwards immediately after the upperguide transition 21.

Each slug has a central channel 32 for engaging the lower guide 13.Sides 33 which are downwardly extending from the body portion 30A flankthis channel 32 and have lower front and rear faces 34 that slopeinwardly of the slug from middle surface portions 35. The

rest of the slug body'portion 30A above the surface portions 35 isstepped back therefrom at 36. It is by abutment of the middle surfaces35 that the slugs push each other between the drive wheels 14. Thebottom 37 of the channel 32 has both its end portions 38 sloped upwardlyto allow the desired tipping. This is also of assistance in tipping ofthe slugs prior to leaving a drive wheel as does the taper on the teeth26. In fact, the three factors mentioned are aspects of the same designfeature of prior alignment of the slugs.

The front of a slug ,ll vis brought down into the matching drive wheelnotch until the slug is aligned with its straight path of travel by thetime the centre of the slug reaches the position 23 prior to top deadcentre 22 of the drive wheel.

As shown in FIGS. 4, 5 and 6, each drive wheel 14 comprises an assemblyof two similarly notched wheels 45 and 46 carried on the same shaft 50through a suitable bearing 51 to define spaced toothed portions 47 and48 in register with each other on either side of the plate 49 whoseedges comprise the guide surface 12.

The factthat the slug has a single centrally disposed tooth on each sideleads to a very well balanced and simple structure that is readilyachieved by coining rather than sintering techniques and using, it isenvisaged, nitrided steel with all the attendant advantages. Such teethare relatively large and so contribute to enabling the movement of theslugs radially of a drive wheel without significant loss of drivingefficiency.

I claim:

I. A train printer slug for use with a closed loop guide track havingtwo parallel spaced outer guide tracks for slugs and an inner guidetrack for slugs spaced from and aligned with the gap between the outertracks, the slug comprising a body element having a print characterbearing portion, two parallel side walls flanking said body element toextend from the body element in a direction away from the characterbearing portion to form with the body element a central guide channelfor slidable co-operation with the inner guide track with each said wallproviding on the surface thereof adjacent to the character bearingportion a laterally extending slide surface for sliding abutment withsaid'outer guide tracks; and a drive tooth flanking the central outerportion of each side wall each said tooth being profiled for drivingco-operation with means for driving the slug along the track.

2. A train printer slug as claimed in claim 1, in which each side toothhas a surface which is flush with the slide surface of the adjacent sidewall and which acts as an extension of the slide surface.

3. A train printer cartridge for driving a plurality of noninterconnected toothed print slugs around a closed loop path; includingan-outer guide track unit having two spaced parallel outer guide tracksand an inner guide track spaced from and aligned with the gap betweenthe outer tracks, said guide tracks defining a closed loop with a partcircular section leading into a straight section which is co-operablewith arectilinear printing station, a drive wheel assembly at said partcircular section including on each side of the inner guide track atoothed wheel for meshing with the teeth on the slugs, the axes ofrotation of the wheels lying-upon a perpendicular to the adjacent end ofthe inner track straight section; said outer track unit being so curvedabout and spaced from the inner track unit that the slugs during theirtransit around the part circular section can be displaced radiallyoutwardly into a nonabutting position whilst maintaining drivingengagement with the teeth and that the end of the straight section ofthe outer track is extended relative to that of the inner track tooverlie a portion of the part circular section of the inner track theportion of the outer track'circular section merging with the extendedstraight portion being shaped to enable alignment of the slugs with thestraight line section to commence in advance of said perpendicularwhereby transformation of angular motion is achieved prior to aslugleaving the drive wheel assembly.

4. A train printer cartridge for driving a plurality of toothed printslugs around a guide track unit having two spaced parallel outer guidetracks defining a continuous slot an inner guide track spaced from andaligned with the slot between the outer tracks said guide tracksdefining a closed loop with a part circular section leading into astraight section which is cooperable with a'rectilinear printing stationand a slug drive assembly, including on each side of the inner guidetrack a toothed wheelfor meshing with the teeth 7 on the slugs, the axesof rotation of the wheels lying on a perpendicular to the adjacent endof the inner track straight section, said slugs each comprising a bodyelement having a print character bearing portion which is able toproject through the slot; two parallel sidewalls flanking said bodyelement to extend from the body element in a direction away from thecharacter bearing portion to form with the body element a control guidechannel for slidable co-operation with the inner guide track and toprovide on the surfaces thereof adjacent to the character bearingportion a laterally extending slide surface for sliding abutment withthe outer guide tracks; and a drive tooth on each side wallfor drivingco-operation with'the toothed wheels said outer track unit being socurved about and spaced from the inner track unit that the slugs duringtheir transit around the in advance of said perpendicular wherebytransformation of angular motion is achieved prior to a slug leaving thedrive wheel assembly.

5. A train printer cartridge as claimed in claim 4, in which each sidetooth of each slug has a slide surface which is flush with the slidesurface of the adjacent side wall thereby to act as a lateral extensionof the slide surface.

1. A train printer slug for use with a closed loop guide track havingtwo parallel spaced outer guide tracks for slugs and an inner guidetrack for slugs spaced from and aligned with the gap between the outertracks, the slug comprising a body element having a print characterbearing portion, two parallel side walls flanking said body element toextend from the body element in a direction away from the characterbearing portion to form with the body element a central guide channelfor slidable cooperation with the inner guide track with each said wallproviding on the surface thereof adjacent to the character bearingportion a laterally extending slide surface for sliding abutment withsaid outer guide tracks; and a drive tooth flanking the central outerportion of each side wall each said tooth being profiled for drivingco-operation with means for driving the slug along the track.
 2. A trainprinter slug as claimed in claim 1, in which each side tooth has asurface which is flush with the slide surface of the adjacent side walland which acts as an extension of the slide surface.
 3. A train printercartridge for driving a plurality of non interconnected toothed printslugs around a closed loop path; including an outer guide track unithaving two spaced parallEl outer guide tracks and an inner guide trackspaced from and aligned with the gap between the outer tracks, saidguide tracks defining a closed loop with a part circular section leadinginto a straight section which is co-operable with a rectilinear printingstation, a drive wheel assembly at said part circular section includingon each side of the inner guide track a toothed wheel for meshing withthe teeth on the slugs, the axes of rotation of the wheels lying upon aperpendicular to the adjacent end of the inner track straight section;said outer track unit being so curved about and spaced from the innertrack unit that the slugs during their transit around the part circularsection can be displaced radially outwardly into a non-abutting positionwhilst maintaining driving engagement with the teeth and that the end ofthe straight section of the outer track is extended relative to that ofthe inner track to overlie a portion of the part circular section of theinner track the portion of the outer track circular section merging withthe extended straight portion being shaped to enable alignment of theslugs with the straight line section to commence in advance of saidperpendicular whereby transformation of angular motion is achieved priorto a slug leaving the drive wheel assembly.
 4. A train printer cartridgefor driving a plurality of toothed print slugs around a guide track unithaving two spaced parallel outer guide tracks defining a continuous slotan inner guide track spaced from and aligned with the slot between theouter tracks said guide tracks defining a closed loop with a partcircular section leading into a straight section which is co-operablewith a rectilinear printing station and a slug drive assembly, includingon each side of the inner guide track a toothed wheel for meshing withthe teeth on the slugs, the axes of rotation of the wheels lying on aperpendicular to the adjacent end of the inner track straight section,said slugs each comprising a body element having a print characterbearing portion which is able to project through the slot; two parallelside walls flanking said body element to extend from the body element ina direction away from the character bearing portion to form with thebody element a control guide channel for slidable co-operation with theinner guide track and to provide on the surfaces thereof adjacent to thecharacter bearing portion a laterally extending slide surface forsliding abutment with the outer guide tracks; and a drive tooth on eachside wall for driving co-operation with the toothed wheels said outertrack unit being so curved about and spaced from the inner track unitthat the slugs during their transit around the part circular section canbe displaced radially outwardly into a non-abutting position whilstmaintaining driving contact with the teeth and that the end of thestraight section of the outer track is extended relative to that of theinner track to overlie a portion of the part circular section of theinner track, the portion of the outer track circular section mergingwith the extended straight portion being shaped to enable the alignmentof the slugs with the straight line section to commence in advance ofsaid perpendicular whereby transformation of angular motion is achievedprior to a slug leaving the drive wheel assembly.
 5. A train printercartridge as claimed in claim 4, in which each side tooth of each slughas a slide surface which is flush with the slide surface of theadjacent side wall thereby to act as a lateral extension of the slidesurface.